Cancer of the pancreas is one of the leading causes of death among cancer patients. This can be attributed in part to the fact that a definitive diagnosis is usually made only at an advanced stage of the disease. We have shown, using positron emission computerized tomography (positron ECT) that 11C-labeled DL-tryptophan and DL valine have high preferential uptakes in normal pancreatic tissue. Sine the L-isomers of these two amino acids have an affinity for normal pancreas while the D-isomers tend to be preferentially taken up by tumor tissue, approximately the same 11C concentrations occur in both normal and malignant pancreatic tissues with the DL mixture. We propose to use 11C-labeled L-tryptophan or L-valine to detect pancreatic cancer as zones of decreased or absent 11C concentrations in the pancreas in the three-dimensional cross-sectional image obtained with positron ECT. Confirmation of the presence of a malignant lesion(s) would then be made with 11C-labeled 1-aminocyclopentanecarboxylic acid or its cyclobutane analog, radiopharmaceuticals which we have shown to have no affinity for inflammatory lesions and to be effective tumor-localizing agents. This diagnostic protocol should thus provide a non-invasive method for differential diagnosis of pancreatic disease. The studies will be done with an up-to-date emission computerized tomograph, an EG&G ORTEC ECAT-II (TM). We also propose to use positron ECT to quantitatively measure the effect of therapy on the extraction/utilization of amino acids by pancreatic neoplasms as a possible method of metabolically gauging individual responses to treatment.